An image forming apparatus includes an image forming unit to form a developer image on a medium, a heating body to heat the developer image formed on the medium, a heat source provided in the heating body to heat the heating body, and a pressing body arranged opposite to the heating body to permit the medium to pass between the pressing body and the heating body, thereby pressurizing the developer image. The image forming apparatus further includes a controller to drive the heat source, even if the heating body is heated from the room temperature state, and the temperature of the heating body rises higher than the fixing temperature, and then the temperature of the heating body is higher than the fixing temperature.